Conversion of vegetable oils to base oils and transportation fuels

ABSTRACT

The present invention is directed to methods (processes) and systems for processing triglyceride-containing, biologically-derived oils to provide for base oils and transportation fuels, wherein partial oligomerization of fatty acids contained therein provide for an oligomerized mixture from which the base oils and transportation fuels can be extracted. Such methods and systems can involve an initial hydrotreating step or a direct isomerization of the oligomerized mixture.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application for patent is a Continuation of U.S. patent applicationSer. No. 12/179,428, filed Jul. 24, 2008.

FIELD OF THE INVENTION

This invention relates generally to fuels and lubricants derived frombiomass, and specifically to methods and systems for efficiently makingbase oils and transportation fuels from vegetable or crop oils.

BACKGROUND

Biofuels are of increasing interest for a number of reasons including:(1) they are a renewable resource, (2) their production is lessdependent on geopolitical considerations, (3) they provide thepossibility of a direct replacement of petroleum-based fuels in existingvehicles, and (4) the net greenhouse gas emissions can be substantiallyreduced by virtue of CO₂ uptake by biofuel precursors—particularly inthe case of cellulosic feedstocks. See Pearce, “Fuels Gold,” NewScientist, 23 September, pp. 36-41, 2006.

An easily-obtainable biofuel is vegetable oil, which largely comprisestriglycerides and some free fatty acids. The properties of vegetableoil, however, make it generally inappropriate for use as a directreplacement for petroleum diesel in vehicle engines, as the vegetableoils' viscosities are generally too high and do not burn cleanly enough,thereby leaving damaging carbon deposits on the engine. Additionally,vegetable oils tend to gel at lower temperatures, thereby hinderingtheir use in colder climates. These problems are mitigated when thevegetable oils are blended with petroleum fuels, but still remain animpediment for long-term use in diesel engines. See Pearce, 2006; Huberet al., “Synthesis of Transportation Fuels from Biomass: Chemistry,Catalysts, and Engineering,” Chem. Rev., vol. 106, pp. 4044-4098, 2006.

Transesterification is currently a method used to convert vegetable oilsinto diesel-compatible fuels (i.e., conventional biodiesel) that can beburned in conventional diesel engines. See, e.g., Meher et al.,“Technical Aspects of Biodiesel Production by Transesterification—AReview,” Renew. & Sustain. Energy Rev., vol. 10, pp. 248-268, 2006.However, a similar cold flow problem with conventional biodiesel fuelsstill remains. This problem is at least partly due to the fact that atlower temperatures, e.g., around freezing (ca. 0° C.), biodiesel oftenthickens and does not flow as readily. Conventional biodiesel isprimarily composed of methyl esters which have long straight chainaliphatic groups attached to a carbonyl group. Also, thetransesterification of vegetable oils exhibits a problem of producingmore than 90% diesel range fuels with little or no kerosene or gasolinerange fractions, thereby limiting the types of fuels produced therefrom.For the conversion of vegetable and other oils to some fuels (e.g.,non-diesel), it is likely that the oils must first be converted toalkanes (paraffins).

It is also worth noting that unsaturation in the fatty acids (obtainedfrom the vegetable oil) contributes to poor oxidation stability anddeposits, and that while hydrogenation will generally improve theoxidation stability of the fuel, it can make the already poor lowtemperature performance of the fuel even worse. Isomerization of theparaffins can ameliorate this problem.

Accordingly, methods and systems for efficiently processing vegetableand/or crop oils into a broader range of fuel types and lubricants,often simultaneously, would be highly beneficial.

BRIEF DESCRIPTION OF THE INVENTION

In some embodiments, the present invention is directed to methods (i.e.,processes) and systems for processing triglyceride-containing,biologically-derived oils, so as to produce base oils and transportationfuels, wherein such processing can initially proceed via hydrotreating(Type 1) or direct isomerization (Type 2). In all such cases, theprocessing effects at least a partial oligomerization of fatty acidcomponents of the biologically-derived oils. In some such embodiments,such oligomerization serves to increase the carbon number of at leastsome of the product, so as to afford a broader range of base oils andlubricant compositions. The multiple product streams afforded by somesuch systems/methods (e.g., diesel fuel+high-value lubricants) serve toenhance the economics of these systems/methods over that of therespective systems/methods that provide for single product streams.

In some embodiments, the present invention is directed to one or moremethods of a first type (Type 1 Methods) for producing base oil anddiesel or other transportation fuel, the methods comprising the stepsof: (a) processing a triglyceride-containing vegetable oil to effectoligomerization (e.g., dimerization) and deoxygenation (e.g.,elimination of carboxyl, carbonyl, and/or hydroxyl moieties) ofunsaturated fatty acid components contained therein so as to provide foran oligomerized mixture, wherein said processing comprises hydrotreatingand subsequent water removal; (b) isomerizing the oligomerized mixtureover an isomerization catalyst to yield an isomerized mixture, whereinthe isomerized mixture comprises a base oil component and a diesel fuelcomponent, and wherein the isomerized mixture comprises at least 10 wt.% alkanes (paraffins) having a carbon number of 30 or greater; and (c)distilling the isomerized mixture to yield/produce a base oil and adiesel fuel.

In some embodiments, the present invention is directed to one or moresystems of a first type (Type 1 Systems) for producing base oil anddiesel fuel processing triglyceride-containing, biologically-derived(e.g., vegetable- or crop-based) oil, such systems comprising thefollowing elements: (a) a processing subsystem for processing atriglyceride-containing vegetable oil so as to effect oligomerizationand deoxygenation of unsaturated fatty acid components containedtherein, thereby providing for an oligomerized mixture, wherein saidprocessing comprises hydrotreating and subsequent water removal; (b) anisomerization unit for isomerizing the oligomerized mixture over anisomerization catalyst to yield an isomerized mixture, wherein theisomerized mixture comprises a base oil component and a diesel fuelcomponent, and wherein the isomerized mixture comprises at least 10 wt.% alkanes having a carbon number of 30 or greater; and (c) adistillation unit for distilling the isomerized mixture so as to yield abase oil and a diesel fuel.

In some embodiments, the present invention is directed to one or moremethods of a second type (Type 2 Methods) for producing base oil anddiesel fuel, such methods comprising the steps of (a) processing atriglyceride-containing vegetable oil to effect oligomerization ofunsaturated fatty acid components contained therein so as to provide foran oligomerized mixture; (b) isomerizing the oligomerized mixture overan isomerization catalyst to yield an isomerized mixture, wherein theisomerized mixture comprises a base oil component and a diesel fuelcomponent; (c) stripping the isomerized mixture of water to yield a dryisomerized mixture, wherein the dry isomerized mixture comprises atleast 10 wt. % alkanes having a carbon number of 30 or greater; (d)separating the dry isomerized mixture into a lower boiling fraction fromwhich diesel fuel is subsequently derived, and a higher boilingfraction; and (e) subsequently further isomerizing at least a portion ofthe higher boiling fraction to yield a base oil.

In some embodiments, the present invention is directed to one or moresystems of a second type (Type 2 Systems) for processingtriglyceride-containing, biologically-derived oil, such systemscomprising the following elements: (a) a processing subsystem forprocessing a triglyceride-containing vegetable oil so as to effectoligomerization of unsaturated fatty acid components contained therein,and thereby provide for an oligomerized mixture; (b) a firstisomerization unit for isomerizing the oligomerized mixture so as toyield an isomerized mixture, wherein the isomerized mixture comprises abase oil component and a diesel fuel component; (c) a stripper forstripping the isomerized mixture of water so as to yield a dryisomerized mixture, wherein the dry isomerized mixture comprises atleast 10 wt. % alkanes having a carbon number of 30 or greater; (d) aseparation unit for separating the dry isomerized mixture into a lowboiling fraction from which diesel fuel is subsequently derived, and ahigh boiling fraction; and (e) a second isomerization unit forsubsequently further isomerizing the high boiling fraction to yield abase oil.

The foregoing has outlined rather broadly features of the presentinvention in order that the detailed description of the invention thatfollows may be better understood. Additional features and advantages ofthe invention will be described hereinafter which form the subject ofthe claims of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts, in stepwise fashion, Type 1 methods for processingtriglyceride-containing oil of biological origin so as to yield base oiland product fuel, in accordance with some embodiments of the presentinvention;

FIG. 2 illustrates an exemplary Type 1 system for implementing methodsof the type depicted in FIG. 1;

FIG. 3 depicts, in stepwise fashion, Type 2 methods for processingtriglyceride-containing oil of biological origin so as to yield base oiland product fuel, in accordance with some alternative embodiments of thepresent invention; and

FIG. 4 illustrates an exemplary Type 2 system for implementing methodsof the type depicted in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION 1. Introduction

Embodiments of the present invention are directed to methods (processes)and systems for processing triglyceride-containing, biologically-derivedoils so as to effect oligomerization and deoxygenation of unsaturatedfatty acid (carboxylic acid) components contained therein, en route tothe production of base oils and transportation fuels (e.g., dieselfuel). Processing in such methods and systems effects at least a partialoligomerization (e.g., dimerization) of the fatty acid components. Insome such methods and systems (Type 1), the processing proceeds via aninitial hydrotreating, whereas in other such methods and systems (Type2), the processing proceeds directly via an isomerizing step.

In view of the above-described limitations of the prior art, advantagesof the methods and systems of the present invention include, but are notlimited to, the generation of multiple product streams, and the abilityto integrate one or more of these streams with traditional refinerystreams and processes.

2. Definitions

Certain terms and phrases are defined throughout this description asthey are first used, while certain other terms used in this descriptionare defined below:

The prefix “bio,” as used herein, refers to an association with arenewable resource of biological origin, such resources generally beingexclusive of fossil fuels.

A “biologically-derived oil,” as defined herein, refers to anytriglyceride-containing oil that is at least partially derived from abiological source such as, but not limited to, crops, vegetables,microalgae, and the like. Such oils may further comprise free fattyacids. The biological source is henceforth referred to as “biomass.” Formore on the advantages of using microalgae as a source of triglycerides,see R. Baum, “Microalgae are Possible Source of Biodiesel Fuel,” Chem. &Eng. News, vol. 72 (14), pp. 28-29, 1994.

“Triglyceride,” as defined herein, refer to class of molecules havingthe following molecular structure:

where x, y, and z can be the same or different, and wherein one or moreof the branches defined by x, y, and z can have unsaturated regions.

A “carboxylic acid” or “fatty acid,” as defined herein, is a class oforganic acids having the general formula:

where “R” is generally a saturated (alkyl)hydrocarbon chain or a mono-or polyunsaturated (alkenyl)hydrocarbon chain, wherein such unsaturationis provided by one or more carbon-carbon double bonds (C═C) in saidchain.

“Lipids,” as defined herein, broadly refers to the class of moleculescomprising fatty acids, and tri-, di-, and monoglycerides.

“Hydrolysis” of triglycerides yields free fatty acids and glycerol, suchfatty acid species also commonly referred to as carboxylic acids (seeabove).

“Transesterification,” or simply “esterification,” refers to thereaction between a fatty acid and an alcohol to yield an ester species.

“Oligomerization,” as defined herein, refers to additive reaction oflike or similar molecules (i.e., “mers”) to form a larger molecule. Forexample, unsaturated fatty acids of the present invention can react orcombine via the double bonds in their structures. When two such speciescombine to form a larger molecule, the resulting species is termed a“dimer.” When, for example, the aforementioned fatty acid componentscontain multiple regions of unsaturation, oligomers comprised of threeor more mers are possible (e.g., “trimers”).

“Hydroprocessing” or “hydrotreating” refers to processes or treatmentsthat react a hydrocarbon-based material with hydrogen, typically underpressure and with a catalyst (hydroprocessing can be non-catalytic).Such processes include, but are not limited to, hydrodeoxygenation (ofoxygenated species), hydrotreating, hydrocracking, hydroisomerization,and hydrodewaxing. For examples of such processes, see Cash et al., U.S.Pat. No. 6,630,066; and Elomari, U.S. Pat. No. 6,841,063. Embodiments ofthe present invention utilize such hydroprocessing to converttriglycerides to paraffins. The terms “hydroprocessing” and“hydrotreating” are used interchangeably herein.

“Hydrofinishing,” as defined herein, refers to the treatment of ahydrocarbon-based material with hydrogen under conditions typically lesssevere than those of hydrotreating, so as to remove impurities and/orimprove one or more physical properties (e.g., color, viscosity,oxidation stability, etc.), thereby rendering an improved product.

“Isomerizing,” as defined herein, refers to catalytic processes thattypically convert n-alkanes to branched isomers. ISODEWAXING (Trademarkof CHEVRON U.S.A. INC.) catalysts are representative catalysts used insuch processes. See, e.g., Zones et al., U.S. Pat. No. 5,300,210;Miller, U.S. Pat. No. 5,158,665; and Miller, U.S. Pat. No. 4,859,312.

“Transportation fuels,” as defined herein, refer to hydrocarbon-basedfuels suitable for consumption by vehicles. Such fuels include, but arenot limited to, diesel, gasoline, jet fuel and the like.

“Diesel fuel,” as defined herein, is a material suitable for use indiesel engines and conforming to the current version at least one of thefollowing specifications: ASTM D 975—“Standard Specification for DieselFuel Oils”; European Grade CEN 90; Japanese Fuel Standards JIS K 2204;The United States National Conference on Weights and Measures (NCWM)1997 guidelines for premium diesel fuel; and The United States EngineManufacturers Association recommended guideline for premium diesel fuel(FQP-1A).

“Lubricants,” as defined herein, are substances (usually a fluid underoperating conditions) introduced between two moving surfaces so toreduce the friction and wear between them. “Base oils” used as/in motoroils are generally classified by the American Petroleum Institute asbeing mineral oils (Group I, II, and III) or synthetic oils (Group IVand V). See American Petroleum Institute (API) Publication Number 1509.Typically, for lubricants, one or more additives are added to base oilto improve one or more of its properties and make it more suitable for adesired lubricant application.

“Viscosity,” can generally be viewed herein, as it is colloquially, as afluid's resistance to flow. In many situations, viscosity is moreconveniently expressed in terms of “kinematic viscosity” having units ofcentistokes (cSt).

“Viscosity index” or “VI,” as defined herein, refers to an index createdby the Society of Automotive Engineers (SAE) to index changes in alubricant's viscosity with variations in temperature, wherein theviscosity of a lubricant with a higher VI will be less dependent ontemperature than the viscosity of a lubricant with a lower VI.Historically, since the index's temperature boundaries are 100° F. (40°C.) and 210° F. (100° C.), the original scale spanned only from VI=0(worst oil) to VI=100 (best oil). However, since the conception of thescale, better oils (e.g., synthetic oils) have been produced, leading toVIs greater than 100.

“Pour point,” as defined herein, represents the lowest temperature atwhich a fluid will pour or flow. See, e.g., ASTM International StandardTest Methods D 5950-96, D 6892-03, and D 97.

“Cloud point,” as defined herein, represents the temperature at which afluid begins to phase separate due to crystal formation. See, e.g., ASTMStandard Test Methods D 5773-95, D 2500, D 5551, and D 5771.

As defined herein, “C_(n),” where “n” is an integer, describes ahydrocarbon or hydrocarbon-containing molecule or fragment (e.g., analkyl or alkenyl group) wherein “n” denotes the number of carbon atomsin the fragment or molecule—irrespective of linearity or branching.

3. Methods of the First Type

As mentioned previously, and with reference to FIG. 1, in someembodiments the present invention is directed to one or more methods forproducing base oil and diesel fuel, the methods comprising the steps of:(Step 101) processing a triglyceride-containing vegetable oil to effectoligomerization and deoxygenation of unsaturated fatty acid componentscontained therein so as to provide for an oligomerized mixture, whereinsaid processing comprises hydrotreating and subsequent water removal;(Step 102) isomerizing the oligomerized mixture over an isomerizationcatalyst to yield an isomerized mixture, wherein the isomerized mixturecomprises a base oil component and a diesel fuel component, and whereinthe isomerized mixture comprises at least 10 wt. % alkanes having acarbon number of 30 or greater; and (Step 103) distilling the isomerizedmixture to yield a base oil and a diesel fuel. In some such methodembodiments, there further (optionally) comprises a step (Step 104) ofhydrofinishing the base oil to yield a hydrofinished base oil.

In some embodiments, such above-described methods further comprise aninitial step of subjecting biomass to an extraction process, whereinsaid extraction process provides for a quantity oftriglyceride-containing vegetable oil. Typically, such an extractionprocess involves solvent extraction. Such processes are well-known tothose of skill in the art. See, e.g., Hoeksema, U.S. Pat. No. 6,166,231.

In some such above-described method embodiments, the step of processingfurther comprises an initial substep of hydrolyzing the triglyceridescontained within the vegetable oil so as to yield free fatty acids. Suchhydrolysis can be acid- or base-catalyzed. Hydrolysis of triglyceridesto yield free fatty acids and glycerol is well-established and known tothose of skill in the art. See, e.g., Logan et al., U.S. Pat. No.4,218,386.

While not intending to be bound by theory, the above-describedoligomerization is thought to occur via additive coupling reactionsbetween fatty acid components having regions of unsaturation. Note that,depending on the embodiment, oligomerization can occur beforehydrotreating, during hydrotreating, and before and duringhydrotreating. Typically, such oligomerization would bethermally-driven, but it is envisioned that this could additionally oralternatively be chemically- or catalytically-induced.

In some such above-described method embodiments, the oligomerizedmixture comprises an oligomer component, wherein the oligomer componentof said mixture comprises at least about 50 wt. % dimer (dimeric)species (i.e., dimers resulting from the dimerization of unsaturatedfatty acid components). In some other embodiments, the oligomercomponent comprises at least 50 wt. % dimer species.

In some such above-described embodiments, there is a sub-step ofincreasing the unsaturated fatty acid component concentration prior tooligomerization. This can be done, for example, using fractionalcrystallization methods. See, e.g., Rubin et al., U.S. Pat. No.4,792,418; and Saxer, U.S. Pat. No. RE 32,241. Such a concentrationenhancement of the unsaturated species can yield oligomerized mixtureswith higher oligomer content.

In some such above-described method embodiments, the vegetable or otherbiologically-derived oil originates from a biomass source selected fromthe group consisting of crops, vegetables, microalgae, and combinationsthereof. Those of skill in the art will recognize that generally anybiological source of lipids can serve as the biomass from which thebiologically-derived oil comprising triglycerides can be obtained. Itwill be further appreciated that some such sources are more economicaland more amenable to regional cultivation, and also that those sourcesfrom which food is not derived may be additionally attractive (so as notto be seen as competing with food). Exemplary biologically-derivedoils/oil sources include, but are not limited to, canola, soy, rapeseed,palm, peanut, jatropha, yellow grease, algae, and the like.

In some such above-described method embodiments, the sub-process ofhydrotreating involves a hydroprocessing/hydrotreating catalyst and ahydrogen-containing environment. In some such embodiments, the activehydrotreating catalyst component is a metal or alloy selected from thegroup consisting of cobalt-molybdenum (Co—Mo) catalyst,nickel-molybdenum (Ni—Mo) catalyst, noble metal catalyst, andcombinations thereof. Such species are typically supported on arefractory oxide support (e.g., alumina or SiO₂—Al₂O₃). Hydrotreatingconditions generally include temperature in the range of about 550° F.to about 800° F.; and H₂ partial pressure generally in the range ofabout 400 pounds-force per square inch gauge (psig) to about 2000 psig,and typically in the range of about 500 psig to about 1500 psig. For ageneral review of hydroprocessing/hydrotreating, see, e.g., Rana et al.,“A Review of Recent Advances on Process Technologies for Upgrading ofHeavy Oils and Residua,” Fuel, vol. 86, pp. 1216-1231, 2007. For anexample of how triglycerides can be hydroprocessed to yield a paraffinicproduct, see Craig et al., U.S. Pat. No. 4,992,605.

In some such above-described method embodiments, the subsequent waterstripper. Other devices and methods for water removal canalso/alternatively be employed. Such devices/methods are known to thoseof skill in the art.

Generally, the step of isomerizing is carried out using an isomerizationcatalyst. Suitable such isomerization catalysts can include, but are notlimited to Pt or Pd on a support such as, but further not limited to,SAPO-11, SM-3, SSZ-32, ZSM-23, ZSM-22; and similar such supports. Insome or other embodiments, the step of isomerizing involves a Pt or Pdcatalyst supported on an acidic support material selected from the groupconsisting of beta or zeolite Y molecular sieves, SiO₂, Al₂O₃,SiO2—Al₂O₃, and combinations thereof. In some such embodiments, theisomerization is carried out at a temperature between about 500° F. andabout 750° F., and typically between 550° F. and about 750° F. Theoperating pressure is typically 200 psig to 2000 psig, and moretypically 200 psig to 1000 psig. Hydrogen flow rate is typically 50 to5000 standard cubic feet/barrel (SCF/barrel). For other suitableisomerization catalysts, see, e.g., Zones et al., U.S. Pat. No.5,300,210; Miller, U.S. Pat. No. 5,158,665; and Miller, U.S. Pat. No.4,859,312.

With regard to the catalytically-driven isomerizing step describedabove, in some embodiments, the methods described herein may beconducted by contacting the n-paraffinic product with a fixed stationarybed of catalyst, with a fixed fluidized bed, or with a transport bed. Inone presently contemplated embodiment, a trickle-bed operation isemployed, wherein such feed is allowed to trickle through a stationaryfixed bed, typically in the presence of hydrogen. For an illustration ofthe operation of such catalysts, see Miller et al., U.S. Pat. Nos.6,204,426 and 6,723,889.

In some such above-described embodiments, the isomerized mixture cancomprise at least 20 wt. % alkanes having a carbon number of 30 orgreater, and in others it can comprise at least 30 wt. % alkanes havinga carbon number of 30 or greater. While not intending to be bound bytheory, it is believed that oligomerization (and subsequentdeoxygenation) of fatty acid components of the vegetable oil areprimarily responsible for such high levels of alkanes of C_(n≦30).

In some embodiments, the step of distilling employs a distillationcolumn (unit) to separate the base oil and diesel fuel into individualfractions. Generally, the base oil is collected in a high-boilingfraction and the diesel fuel is collected in a low-boiling fraction. Insome particular embodiments, a fractional bifurcation occurs at oraround 650° F., in which case the diesel fuel is largely containedwithin a 650° F.− fraction (boiling below 650° F.) and the base oil iscontained within a 650° F.+ fraction (boiling above 650° F.). Those ofskill in the art will recognize that there is some flexibility incharacterizing the high and low boiling fractions, and that the products(base oil and diesel fuel) may be obtained from “cuts” at varioustemperature ranges.

In some embodiments, the diesel fuel produced comprises at least 70 wt.% C₁₂ to C₁₈ alkanes. In some or other such embodiments, the diesel fuelhas a pour point of less than −10° C. In some embodiments, the base oilproduced has a pour point of less than −10° C. In some or still othersuch embodiments, the base oil has a viscosity index of generallygreater than 120, and typically greater than 130.

With regard to the optional hydrofinishing step 104, this generallyserves to improve color, and oxidation and thermal stability.

In some such above-described method embodiments, the base oils producedin Step 103 and/or Step 104 are suitable for use as, and/or inclusionin, synthetic biolubricants, and/or other such formulations that impartlubricity. In some embodiments, such above-described methods furthercomprise a step of blending the base oils with one or more esterspecies. In some or still other embodiments, such above-describedmethods further comprise a step of blending the produced base oils witha conventionally-derived base oil selected from the group consisting ofGroup I oils, Group II oils, Group III oils, and combinations thereof.

4. Systems of the First Type

As already mentioned in a previous section, and with reference to FIG.2, in some embodiments the present invention is directed to one or moresystems (e.g., system 200) for processing triglyceride-containing,biologically-derived oil, such systems (200) comprising the followingelements: a processing subsystem (201) for processing atriglyceride-containing vegetable oil so as to effect oligomerizationand deoxygenation of unsaturated fatty acid components containedtherein, thereby providing for an oligomerized mixture, wherein saidprocessing comprises hydrotreating (via hydrotreating subunit 201 b) andsubsequent water removal (via stripper 201 c); an isomerization unit(202) for isomerizing the oligomerized mixture over an isomerizationcatalyst to yield an isomerized mixture, wherein the isomerized mixturecomprises a base oil component and a diesel fuel component, and whereinthe isomerized mixture comprises at least 10 wt. % alkanes having acarbon number of 30 or greater, typically 20 wt. % such alkanes, andmore typically 30 wt. % such alkanes; and a distillation unit (203) fordistilling the isomerized mixture so as to yield a base oil and a dieselfuel. In some such embodiments, such systems further comprise ahydrofinishing unit (204) for hydrofinishing the base oil.

In some such above-described embodiments, the processing subsystemfurther comprises a hydrolysis reactor (201 a) for initially hydrolyzingthe triglycerides contained within the vegetable oil so as to yield freefatty acids.

Generally, all of the above-described systems and corresponding unitsare configured for processing a triglyceride-containing,biologically-derived oil in accordance with one or more of the methodsdescribed in Section 3. Further, there is typically a proximalrelationship between the various units that comprise system 200, butthis need not be the case. Such relationships may be influenced byexisting infrastructure and/or other economic considerations.

5. Methods of the Second Type

Referring now to FIG. 3, in some embodiments, the present invention isdirected to one or more methods for producing base oil and diesel fuel,such methods comprising the steps of: (Step 301) processing atriglyceride-containing vegetable oil to effect oligomerization ofunsaturated fatty acid components contained therein so as to provide foran oligomerized mixture; (Step 302) isomerizing the oligomerized mixtureover an isomerization catalyst to yield an isomerized mixture, whereinthe isomerized mixture comprises a base oil component and a diesel fuelcomponent; (Step 303) stripping the isomerized mixture of water to yielda dry isomerized mixture, wherein the dry isomerized mixture comprisesat least 10 wt. % alkanes having a carbon number of 30 or greater; (Step304) separating the dry isomerized mixture into a lower boiling fractionfrom which diesel fuel is subsequently derived, and a higher boilingfraction; and (Step 305) subsequently isomerizing at least a portion ofthe higher boiling fraction to yield a base oil. Similar to the methodsdescribed in Section 3, in some such embodiments, such methods furthercomprise a step of hydrofinishing the base oil to yield a hydrofinishedbase oil.

In some such above-described method embodiments, the vegetable oilcomprises one or more biologically-derived oils selected from the groupconsisting of canola, soy, rapeseed, palm, peanut, jatropha, yellowgrease, algae, and combinations thereof.

In some such above-described method embodiments, the oligomerizedmixture comprises an oligomer component, said oligomer componentcomprising at least about 50 wt. % dimer species, and more typically atleast about 70 wt. % dimer species.

In some such above-described method embodiments, the step of isomerizingis carried out at a temperature of between 550° F. and 750° F., usingany one of a variety of isomerization catalysts.

In some such above-described method embodiments, the isomerized mixturecan comprise at least about 20 wt. % alkanes having a carbon number of30 or greater, and in some cases it can comprise at least about 30 wt. %alkanes having a carbon number of 30 or greater.

In some such above-described method embodiments, the diesel fuelcomprises at least 70 wt. % C₁₂ to C₁₈ alkanes. In these or otherembodiments, the diesel fuel has a pour point of less than −10° C.

In some such above-described method embodiments, the base oil has a pourpoint of less than −10° C. In these or other embodiments, the base oilhas a viscosity index of greater than 120.

In some such above-described method embodiments, the hydrofinished baseoil has a pour point of less than −10° C. In these or other embodiments,the hydrofinished base oil has a viscosity index of greater than 120.

Generally, to the extent that they share common steps, aspects of theType 2 methods are consistent with those of the Type 1 methods describedin Section 3. For example, processing Step 301 may further comprise asub-step of hydrolyzing the triglycerides such as described for some ofthe Type 1 methods above. Similarly, concentration of oligomeric speciesin the oligomerized mixture can be effected via fractionalcrystallization methods, as described above.

6. Systems of the Second Type

Referring now to FIG. 4, in some embodiments, the present invention isdirected to one or more systems (e.g., system 400) for processingtriglyceride-containing, biologically-derived oil, such systemscomprising the following elements: (a) a processing subsystem (401) forprocessing a triglyceride-containing vegetable oil so as to effectoligomerization of unsaturated fatty acid components contained therein,and thereby provide for an oligomerized mixture; (b) a firstisomerization unit (402) for isomerizing the oligomerized mixture so asto yield an isomerized mixture, wherein the isomerized mixture comprisesa base oil component and a diesel fuel component; (c) a stripper (403)for stripping the isomerized mixture of water so as to yield a dryisomerized mixture, wherein the dry isomerized mixture comprises atleast 10 wt. % alkanes having a carbon number of 30 or greater; (d) aseparation unit (404) for separating the dry isomerized mixture into alow boiling fraction from which diesel fuel is subsequently derived, anda high boiling fraction; and (e) a second isomerization unit (405) forsubsequently isomerizing the high boiling fraction to yield a base oil.In some such embodiments, such systems further comprise a hydrofinishingunit (406) for hydrofinishing the base oil to yield a hydrofinished baseoil.

Generally, all of the above-described systems and corresponding unitsare configured for processing a triglyceride-containing,biologically-derived oil in accordance with one or more of the methodsdescribed in Section 5. Furthermore, as in the case of Type 1 systems,there is typically a proximal relationship between the various unitsthat comprise system 400, but this need not be the case. Suchrelationships may be influenced by existing infrastructure and/or othereconomic considerations.

7. Variations

In some Type 2 methods, hydroprocessing may be a sub-process of theinitial processing step. Some such variation embodiments may begin toconverge on the methods of Type 1. Similar observations may be maderegarding the corresponding systems.

In some embodiments of Type 1 and Type 2 methods, the initial processingstep and the isomerizing step are fully or partially integrated suchthat these processes are carried out simultaneously.

In some presently-contemplated embodiments, the methods and/or systemsof the present invention can be fully or partially integrated withconventional refinery processes—particularly in situations wherein suchintegration provides for a synergistic enhancement of the productioneconomics.

In some or other such variant embodiments, non-crop sources oftriglyceride-containing oil can be mixed or admixed with thebiologically-derived oil used herein.

The transportation fuels produced by the methods/systems of the presentinvention can extend beyond diesel fuel. Those of skill in the art willrecognize that the composition of the resulting transportation fuel willbe a function of the chain length of the carboxylic acid components ofthe triglyceride-bearing, biologically-derived oil.

8. Example

The following example is provided to demonstrate particular embodimentsof the present invention. It should be appreciated by those of skill inthe art that the methods disclosed in the example which follows merelyrepresent exemplary embodiments of the present invention. However, thoseof skill in the art should, in light of the present disclosure,appreciate that many changes can be made in the specific embodimentsdescribed and still obtain a like or similar result without departingfrom the spirit and scope of the present invention.

This Example serves to illustrate a method of processing a vegetable oilen route to forming a transportation fuel and a base oil, in accordancewith some embodiments of the present invention.

Canola oil was hydrotreated over a Ni—Mo/Al₂O₃ hydrotreating catalystunder the following conditions: 1000 psig, 5000 scf/bbl H₂, 1.66 LHSV(liquid hourly space velocity), and 610° F. This reactor was followed bya second reactor containing a Pt on SM-3 sieve isomerization catalyst,also at 1.66 LHSV and a temperature of 700° F. Processing conditionseffected a “conversion yield” as follows: 92 weight percent of thecanola oil was converted from 650° F.+ to 650° F.−. Upon distillation,the fraction boiling below 650° F. (650° F.−) was predominately aparaffinic diesel, while the fraction boiling above 650° F. (650° F.+)was comprised primarily of oligomerized (primarily dimerized) species(gas chromatography/mass spectral analysis yielding a mass distributioncentered around a C₃₆ paraffin (alkane). This 650° F.+ fraction had aviscosity at 100° C. of 3.8 centistokes (cSt), a pour point of +18° C.,and a viscosity index (VI) of 151. This oil was further isomerized overPt on SM-3 at 600° F. to give a 3.3 cSt oil of −10° C. pour point, −4°C. cloud point, and 204 VI.

9. Conclusion

The foregoing describes methods and systems for processingtriglyceride-containing, biologically-derived oils to efficiently yielda combination of transportation fuels and base oils. Such methods andsystems are based on an at least partial oligomerization of thecarboxylic acid components contained within the triglyceride-containing,biologically-derived oil. Such methods and systems are economicallyadvantageous as they provide for multiple product streams.

All patents and publications referenced herein are hereby incorporatedby reference to the extent not inconsistent herewith. It will beunderstood that certain of the above-described structures, functions,and operations of the above-described embodiments are not necessary topractice the present invention and are included in the descriptionsimply for completeness of an exemplary embodiment or embodiments. Inaddition, it will be understood that specific structures, functions, andoperations set forth in the above-described referenced patents andpublications can be practiced in conjunction with the present invention,but they are not essential to its practice. It is therefore to beunderstood that the invention may be practiced otherwise than asspecifically described without actually departing from the spirit andscope of the present invention as defined by the appended claims.

1. A method for producing base oil and diesel fuel, the methodcomprising the steps of: a) providing for a triglyceride-containingvegetable oil comprising both saturated and unsaturated fatty acidcomponents; b) processing the triglyceride-containing vegetable oil toeffect deoxygenation of saturated fatty acid components andoligomerization and deoxygenation of unsaturated fatty acid componentscontained therein so as-to provide for an oligomerized mixturecomprising an oligomer component, wherein said processing compriseshydrotreating and subsequent water removal; c) isomerizing theoligomerized mixture over an isomerization catalyst to yield anisomerized mixture; wherein the isomerized mixture comprises (i) a baseoil component at least partially-derived from oligomerization anddeoxygenation of the unsaturated fatty acid components, and (ii) adiesel fuel component at least partially-derived from the deoxygenationof the saturated fatty acid components; and wherein the isomerizedmixture comprises at least 10 wt. % oligomers as alkanes having a carbonnumber of 30 or greater and contributing to the base oil component ofthe isomerized mixture; and d) distilling the isomerized mixture toyield a base oil and a diesel fuel.
 2. The method of claim 1, furthercomprising a step of hydrofinishing the base oil.
 3. The method of claim1, wherein the step of processing further comprises an initial substepof hydrolyzing the triglycerides contained within the vegetable oil soas to yield free fatty acids.
 4. The method of claim 1, wherein thevegetable oil comprises one or more biologically-derived oils selectedfrom the group consisting of canola, soy, rapeseed, palm, peanut,jatropha, yellow grease, algae, and combinations thereof.
 5. The methodof claim 1, wherein the oligomer component of the oligomerized mixturecomprises at least 50 wt. % dimer species.
 6. The method of claim 1,wherein the oligomer component of the oligomerized mixture comprises atleast 70 wt. dimer species.
 7. The method of claim 1, whereinoligomerization occurs temporally in a manner selected from the groupconsisting of before hydrotreating, during hydrotreating, and before andduring hydrotreating.
 8. The method of claim 1, wherein oligomeric yieldis enhanced by increasing concentration of unsaturated fatty acidcomponents via fractional crystallization techniques.
 9. The method ofclaim 1, wherein the hydrotreating utilizes a catalyst comprisingnickel-molybdenum on a support selected from alumina or SiO₂—Al₂O₃. 10.The method of claim 1, wherein the hydrotreating is carried out at atemperature between 550° F. and 800° F.
 11. The method of claim 1,wherein the hydrotreating is carried out under a H₂ partial pressure ofbetween 400 psig and 2000 psig.
 12. The method of claim 1, wherein thehydrotreating is carried out under a H₂ partial pressure of between 500psig and 1500 psig.
 13. The method of claim 1, wherein a stripper isused to remove the water.
 14. The method of claim 1, wherein theisomerization catalyst is a noble metal on a SAPO 11 support.
 15. Themethod of claim 1, wherein the step of isomerizing is carried out at atemperature of between 550° F. and 750° F.
 16. The method of claim 1,wherein the isomerized mixture comprises at least 20 wt. % oligomers asalkanes having a carbon number of 30 or greater.
 17. The method of claim1, wherein the isomerized mixture comprises at least 30 wt. % oligomersas alkanes having a carbon number of 30 or greater.
 18. The method ofclaim 1, wherein the diesel fuel comprises at least 70 wt. % C₁₂ to C₁₈alkanes.
 19. The method of claim 1, wherein the diesel fuel has a pourpoint of less than −10° C., and wherein the base oil has a pour point ofless than −10° C.
 20. The method of claim 1, wherein the base oil has aviscosity index of greater than 120, and wherein the base oil has aviscosity index of greater than 130.